In turbine engines, compressed air discharged from a compressor section and fuel introduced from a source of fuel are mixed together and burned in a combustion section, creating combustion products defining hot combustion gases. The combustion gases are directed through a hot gas path in a turbine section, where they expand to provide rotation of a turbine rotor. The turbine rotor may be linked to an electric generator, wherein the rotation of the turbine rotor can be used to power the compressor section and produce electricity in the generator.
One or more conduits, e.g., liners, transition ducts, etc., are typically used for conveying the combustion gases from one or more combustor assemblies located in the combustion section to the turbine section. Due to the high temperature of the combustion gases, the conduits are typically cooled during operation of the engine to avoid overheating.
Prior art solutions for cooling the conduits include supplying a cooling fluid, such as air that is bled off from the compressor section, onto an outer surface of the conduit to provide direct convection cooling to the transition duct. An impingement member or impingement sleeve may be provided about the outer surface of the conduit, wherein the cooling fluid may flow through small holes formed in the impingement member before being introduced onto the outer surface of the conduit. Other prior art solutions inject a small amount of cooling fluid along an inner surface of the conduit to provide film cooling to the inner surface of the conduit.